Professional editors greatly improve the quality of written works, but they are expensive and take time. If you publish a high volume of blog posts, newsletter issues, or other online writings, the cost and time constraints of editors may make hiring them impractical.
Grammar checking tools can help you self edit for publication or polish a draft before handing it to an editor.
ProWritingAid, linked below, is the tool I chose. As a non-native English speaker, I use it all the time for all my writings and it integrates well with the Google ecosystem. It’s freemium, and it strikes a good balance between features and price.